CHICAGO -- The Cook County Jail is downsizing, and it's expected to save taxpayers millions of dollars.

The jail population is down thanks to electronic monitoring, and diverting the mentally ill and non-violent offenders to treatment programs. So Cook County leaders say it doesn't make sense to renovate outdated and underutilized jail buildings.

"Demolishing these jail divisions happens once in a generation - if ever," Cook County Board President Toni Preckwinkle said.

The demolition of Minimum Security Division 3 is already in progress at the sprawling Cook County Jail Campus. The obsolete Divisions 1 and 17 are next in line for the wrecking ball. Preckwinkle and Cook County Sheriff Tom Dart say the savings can now be put towards helping non-violent offenders with drug problems and mental health issues.

For non-violent offenders, Dart says, losing your job while you await trial at the Cook County jail makes things worse for everyone. Dart has supported efforts to re-direct people to community services, with the help of electronic monitoring and other tools, helping reduce the jail population. Preckwinkle said it's down 20% since she took office.

And Sheriff Tom Dart says there are additional savings. Some of the obsolete buildings required more staffing to operate than modernized facilities that use video surveillance systems and more efficient designs. So Dart says through as prison guards retire, there's a savings with manpower through attrition. And staffing levels at the jail have gradually gone down.